Field of the Invention
The present invention relates to blood collection sets for safe and convenient handling of needles used in blood collection procedures. More particularly, the present invention relates to a blood collection set including a safety shield for protecting users from a used needle tip.
Description of Related Art
Disposable medical devices having medical needles are used for administering medication or withdrawing fluid from the body of a patient. Such disposable medical devices typically include blood-collecting needles, fluid handling needles, and assemblies thereof. Current medical practice requires that fluid containers and medical needles used in such devices be inexpensive and readily disposable. Existing blood collection devices often employ some form of durable, reusable holder on which detachable and disposable medical needles and fluid collection tubes may be mounted. A blood collection device of this nature may be assembled prior to use and then discarded after use.
A blood collection device or intravenous (IV) infusion device typically includes a needle cannula having a proximal end, a pointed distal end, and a lumen extending therebetween. The proximal end of the needle cannula is securely mounted in a plastic hub defining a central passage that communicates with the lumen extending through the needle cannula. A thin, flexible thermoplastic tubing is connected to the hub and communicates with the lumen of the needle cannula. The end of the flexible plastic tubing remote from the needle cannula may include a fixture for connecting the needle cannula to a fluid collection tube holder or other receptacle. The specific construction of the fixture will depend upon the characteristics of the receptacle to which the fixture is to be connected.
In order to reduce the risk of incurring an accidental needle-stick wound, protection of used needle cannulas becomes important. With concern about infection and transmission of diseases, methods and devices to enclose or cover the used needle cannula have become very important and in great demand in the medical field. For example, needle assemblies often employ a safety shield that can be moved into shielding engagement with a used needle cannula to minimize risk of an accidental needle stick.
Prior art devices in this area often include flexible wings, which are used as means for securing the needle assemblies to the body of a patient during a medical procedure. Winged needle assemblies typically include a barrel or body portion, a wing portion mounted to the body portion, and a needle cannula. The wing portion can be used to manipulate the assembly during insertion and withdrawal of the needle cannula from the patient. The wing portion is also used to stabilize the assembly against the patient's skin, by providing a surface area for taping, attachment, etc. to the patient to prevent movement of the assembly.
U.S. Pat. No. 7,294,118 to Saulenas et al. discloses a retractable push-button needle assembly, in which a needle is attached to a hub and extends through a barrel. A push-button actuator extends from the hub and is in interference engagement with the barrel. Activation is accomplished with a user actively pushing the push-button into the barrel, thereby causing the needle to retract within the barrel under power of a spring disposed between the hub and the barrel.
Needle assemblies may also incorporate passively activated safety features. In such devices, the needle shielding feature is passively actuated upon normal usage of the device. For example, the activation of the safety feature may automatically occur, such as upon removing an outer safety packaging cover and after releasing the user's grip on the device after insertion of the needle into the patient's injection site. The safety feature may be a safety shield that is propelled toward the needle tip, or a force that is exerted on the needle to retract the needle into the body of the device. U.S. Pat. No. 6,682,510 to Niermann discloses a passive safety blood collection set which includes a tip guard slidably movable along a needle cannula. The tip guard is mounted to a needle hub through a pair of collapsible leaves, which are collapsed onto themselves and held in place by a packaging cover. In use, the practitioner holds the leaves in the collapsed or folded state to remove the cover, and then releases the leaves enabling them to unfold to propel the tip guard distally.
Such passively actuated devices typically involve a relative axial force between the needle and the shield for activation of the safety feature. If this relative axial force is greater than a resisting force supplied by the friction between the needle and the patient's tissue, the needle may be self-ejected from the patient during activation of the safety feature.